For a budget like that? It’ll be very, very, very tough, especially since GPUs have not finished normalizing in price. $500 is the cost of any decent GPU right now, so it’ll take up that entire budget pretty much. I would seriously suggest your friend save up that money. Another $300 would make it a far, far better build.
Something like this is cheapish but won’t be absolute garbage.
(^ cheaper motherboard)
(^ far better motherboard for a little $ more)
If he’s strict on that $500, well, he could always check marketplaces online for used parts. The GPUs will be the hardest to come by, but he could potentially save some $ that way. However, I mean…it’s technically possible, but not advised at all. It would be like burning that money.
(closest to $500 as possible. Again…very much so not advised, for many reasons.)
Here’s a quick difference between the above too, to show how much better it would be for him to save for better parts:
RX 6400 + Ryzen 5 5600x (CPU overkill here; held back)
RX 6400 : Test in 10 Games - AMD RX 6400 Gaming Test - YouTube
RX 6600 + Ryzen 5 3600
AMD RX 6600 8GB Test in 20 Games 1080p and 1440p (Ryzen 5 3600) - YouTube
Finally, here’s a comparison of the build I presented above that’s higher priced, but far better.
RX 6600 + Ryzen 5 5600x
RX 6600 + RYZEN 5 5600X | TEST IN 20 GAMES | 1080p 1440p - YouTube
If he saves and buys then, his PC will also last far longer. He won’t see the terrible performance within the year, but a few years at most. His parts will last longer too, and will deliver better and more stable performances.
(if it helps to know: I have built over 30 PCs for family, friends and strangers across the internet and the few who decided to go for low budget, regretted it within a few months. However it goes, I wish your friend good luck! )